Electro-hydrodynamic (“EHD”) wind energy conversion (“WEC”) is a process wherein electrical energy is extracted directly from wind energy. Just as flakes of snow may be driven by the wind to create a “current” of snowflakes, so too may wind be hydrodynamically coupled to charged species to create a true electrical current in free space. The generated current may be connected to an electrical circuit by means of an electrostatic field to perform useful work.
EHD systems exhibit a number of advantages over conventional wind turbines. For example, conventional wind turbines have a maximum allowable wind speed beyond which their blades, mechanical components, and electrical generating equipment may be damaged. Once this maximum wind speed, or “cut-out” speed, is reached, the wind turbine's blades may begin to furl in order to avoid damage to the turbine. Typical cut-out speeds for small turbines are approximately 28 mph (12.5 m/s). Medium and large turbines may cut out at approximately 60 mph (26.8 m/s).
EHD systems, however, are solid-state devices, with no rotating machinery, shafts, bearings, gears, lubrication oil, brakes, equipment housing, and the like. Thus, EHD systems have no furling speed, and may continue to generate energy from wind even at high wind velocities. Furthermore, even though some large conventional turbines may have a high furling speed, conventional turbines may not produce more than their rated power. Consequently, their power curve is substantially flat above the furling speed, whereas EHD power continues to rise with increasing wind velocity.
At low or medium wind velocities, however, traditional EHD systems are inefficient, and may not generate as much energy as it takes to run them. For example, EHD systems require energy to create the charged species and, in the case of liquid-based charge carriers, energy to pump the liquid and hydraulically pressure spray it to create small diameter particles. Furthermore, traditional EHD systems are expensive, and may not be cost-effective at any wind velocity.
Clearly, a need exists for a cost-effective EHD system that is capable of generating net positive energy at a wide range of wind velocities.